Air filtration systems typically utilize filter holding frames to secure various combinations of ASHRAE prefiltration and final filtration elements into an air duct of an air handling system. In applications requiring high efficiency filters such as 95% DOP filters, HEPA filters and other high efficiency filters, the use of some type of mechanical clamping mechanism is utilized to effectively seal the filter to the holding frame positioned within the air duct. The filter to filter holding frame seal should ensure that any bypass or leakage around the seal is no greater than the maximum penetration of the filter. For example, a HEPA filter with an efficiency of 99.97% has a maximum allowable penetration of 0.03%. Thus, the filter must seal to the filter holding frame effectively enough so that only a maximum of 0.03% leakage occurs between the filter and the filter holding frame.
The need to have clamping devices to seal high efficiency filters and various types of fasteners to secure and hold ASHRAE filters results in a very time consuming and costly process when filters must be removed and/or installed. This is particularly true on large filtration systems where dozens, if not hundreds of filters must be removed and replaced on a regular basis. The use of wrenches, ratchets or other types of tools is often required in order to loosen nuts, bolts, or other fasteners in order to remove the filters from the holding frames or to loosen the filter clamping mechanisms. Further, the clamping devices for holding the filters are bulky and require ample operational space for opening (unclamping) and closing (clamping) about the filters. Thus, the operation of the conventional clamping devices increases the dimensions of the filter housing and/or a reduced filter size must be utilized.
Additionally, while conventional clamping devices may provide acceptable sealing between a final stage filter and the filter holding frame, leakage between a pre-filter and the final stage filter is commonplace. This leakage reduces the lifetime of the final stage filter and increases energy consumption that is needed to move air through the filter.
Thus, there is a need for a filter holding frame with a clamping mechanism that does not require the use of tools to operate, that can be used to effectively secure and seal high efficiency filters in a filter housing, and reduce the operational space required to open and close about the filter, while effectively holding and sealing pre-filters and lower efficiency filters in a location within the filter housing.